(90Cc/70Cc/50Cc-4T); Service Information - KYMCO Mongoose 90 Service Manual

7
. CYLINDER HEAD/VALVES

(90cc/70cc/50cc-4T)

SERVICE INFORMATION

GENERAL INSTRUCTIONS
• The cylinder head can be serviced with the engine installed in the frame.
• When assembling, apply molybdenum disulfide grease or engine oil to the valve guide movable
parts, valve arm and camshaft sliding surfaces for initial lubrication.
• The camshaft is lubricated by engine oil through the cylinder head engine oil passages. Clean and
unclog the oil passages before assembling the cylinder head.
• After disassembly, clean the removed parts and dry them with compressed air before inspection.
• After removal, mark and arrange the removed parts in order. When assembling, install them in
the reverse order of removal.
SPECIFICATIONS
90cc
Item
Valve clearance (cold)
Cylinder head compression pressure 16 kg/cm²(1600 kpa, 227.2 psi)
Cylinder head warpage
Camshaft cam height
Valve rocker arm to shaft clearance
Valve stem-to-guide
clearance
Valve spring free length
Valve spring
compressed force
70cc
Item
Valve clearance (cold)
Cylinder head compression pressure 14 kg/cm²(1400 kpa, 198.8 psi)
Cylinder head warpage
Camshaft cam height
Valve rocker arm to shaft clearance
Valve stem-to-guide
clearance
Valve spring free length
Valve spring
compressed force
IN 0.1 (0.004)
EX 0.1 (0.004)
IN 26.4881 (1.029524)
EX 25.8073 (1.032292)
0.034～0.09 (0.00136～0.0036)
IN 0.01～0.037 (0.0004～0.00148)
EX 0.025～0.052 (0.001～0.00208)
IN 32.3 (1.292)
EX 35 (1.4)
IN 3.47～4.27 kg at 26 mm (1.04 in)
EX 8.29～10.19 kg at 29 mm (1.16 in)
IN 0.04 (0.0016)
EX 0.04 (0.0016)
IN 25.761 (1.03044)
EX 25.604 (1.02416)
0.034～0.09 (0.00136～0.0036)
IN 0.01～0.037 (0.0004～0.00148)
EX 0.025～0.052 (0.001～0.00208)
IN 29.9 (1.196)
EX 33.5 (1.34)
IN 4.3 kg at 22.45 mm (0.898 in)
EX 8.4 kg at 25.25 mm (1.01 in)
Standard
⎯
Standard
⎯
mm (in)
Service Limit
⎯
⎯
⎯
0.05 (0.002)
26.33 (1.0532)
25.65 (1.026)
0.1 (0.004)
0.06 (0.0024)
0.08 (0.0032)
30.8 (1.232)
33.5 (1.34)
⎯
⎯
mm (in)
Service Limit
⎯
⎯
⎯
0.05 (0.002)
25.65 (1.026)
25.5 (1.02)
0.1 (0.004)
0.06 (0.0024)
0.08 (0.0032)
28.4 (1.136)
32 (1.28)
⎯
⎯
7-2